Such methods are used for example in automated transmissions. Such transmissions usually comprise hydraulically actuated disk clutches. When a gearshift is carried out, two or sometimes four clutches are involved. During a gearshift, a first clutch is closed and a second clutch is opened. During this, the first clutch takes over the transmission of torque from the second clutch.
In the case of hydraulically actuated clutches the quality of a shifting operation depends in large measure on the most exact possible pre-filling of the clutch to be closed, with hydraulic fluid. During the use of an automated powershift transmission the coordination of the corresponding filling times takes up not inconsiderable time.
The optimum filling times can vary from one transmission to another, among other things because of manufacturing tolerances. Against that background the document DE 100 51 537 A1 proposes a method for the automatic determination of filling parameters. In this case, while at rest a basic application principle is determined for each clutch.
However, during the life of a transmission the optimum filling times change, for example due to settling of the clutch disks, wear of the clutch linings and sometimes other aging and wear-related changes. Such effects are not taken into account in a basic application principle determined at the beginning of the transmission's life. Furthermore, in automated teach-in routines in most cases an application principle is only learned at a particular operating point, which is then extrapolated with the help of offsets and performance characteristics for the remainder of the working range.